While Nadal, the champion in Melbourne in 2009, has another 17 days before the tournament begins, he feels the virus has left him "unable to get ready in time to tackle the rigours of a grand slam", especially after his six-month absence.

"My knee is much better and the rehabilitation process has gone well as predicted by the doctors but this virus didn't allow me to practise this past week," Nadal, who has also withdrawn from the Qatar Open in Doha, said. "As my team and doctors say, the safest thing is to do things well. I simply would not be doing myself justice if I went down there so unprepared."

The 26-year-old has not competed since June when he suffered a shock defeat at the hands of Lukas Rosol, then ranked 100 in the world, in the second round of Wimbledon. He was forced to miss his Olympic title defence, which he described as one of the saddest moments of his career, and was also ruled out of the US Open and the Davis Cup final, which Spain lost to the Czech Republic.

Nadal is now targeting a return on the clay courts of Acapulco in late February. "I will have to wait until the Acapulco tournament to compete again although I could consider playing before at any other ATP event," he said. "I always said my return will be when I am in the right condition to play, and after all this time away I'd rather not accelerate the comeback and prefer to do things well."

Nadal's absence in Melbourne will be a boost to the rest of the top four – Novak Djokovic, Roger Federer and Andy Murray. Djokovic began preparations for his Australian Open title defence by outclassing David Ferrer in the Abu Dhabi semi-finals on Friday. The world No1, playing his first match since winning the ATP World Tour Finals in November, showed few signs of rust in a 6-0, 6-3 win over the world No5.

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